600V 1.3mμ·cm2 low-leakage low-current-collapse AlGaN/GaN HEMTs with AlN/SiNx passivation

We report a new passivation technique that yields low OFF-state leakage current and greatly suppressed current collapse simultaneously in 600-V AlGaN/GaN high-electron-mobility transistors (HEMTs). This passivation structure consisted of an AlN/SiNx stack with 4-nm epitaxial AlN deposited by plasma-enhanced atomic layer deposition (PEALD) and 50-nm SiN_x deposited by plasma-enhanced chemical vapor deposition (PECVD). The HEMTs with a gate-drain distance of 15 μm deliver a high maximum drain current of 900 mA/mm, a low OFF-state leakage current of 0.7 μA/mm at a drain bias (V_DS) of 600 V, and a steep subthreshold slope of 63 mV/dec. Compared to the dc specific static ON-resistance (Static_R _ON) of 1.3 mΩ cm², the specific dynamic ON-resistance (Dyamic_R _ON) after high OFF-state V_DS stress at 650 V only increased to 2.1 mΩ·cm². At elevated temperatures, the increase in Dyamic_ R_ON was observed to be further suppressed - a highly desirable feature for power electronics applications.